Genus
Tresus (Gaper clams)
Tresus nuttallii. Photo: (c) Ken-ichi Ueda, some rights reserved (CC BY)
Tresus is a genus of saltwater clams, marine bivalve mollusks in the family Mactridae. Many of them are known under the common name the horse clam or as species of gaper clam. They are similar to geoducks.
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